This invention relates to a method for processing wastes from the machining of ferromagnetic materials, and to an apparatus for practicing the method of the invention.
German published patent application No. DE 3,739,496 discloses a band filtering apparatus with which contaminated fluid, especially machining fluid which is used in the cutting of metals, can be cleaned. Such a band filtering apparatus is provided with a dirt chamber to which the fluid is fed. Under this dirt chamber there is a filter base on which there is placed a filter fleece. The filter fleece is advanced automatically step by step in accordance with the amount of waste deposited on it. The wastes are removed from the apparatus with the filter fleece and pass into a container. In addition to a preponderance of metal chips or metal dust, these wastes also contain abrasive residues, such as corundum material. Moreover, these wastes are also heavily laden with oil or emulsion.
The disposal of this mixture without further processing can be performed only by approved refuse disposal companies and only at special dumps. Attempts have already been made to feed this mixture to an incinerator. Due, however, to the metal components as well as corundum, this is an uneconomical and difficult solution. Melting the metals in a melting furnace is also disadvantageous due to their high content of foreign substances.
According to the "Technische Anleitung Abfall" [Technical Instructions Regarding Waste] in force in the Federal Republic of Germany, recycling of wastes is preferred over conventional waste disposal. This regulation expressly applies also to hazardous wastes. The recycling process must meet the requirements that 1) the recycling be technically possible; 2) the recycling costs be reasonable, and 3) that a market exists or can be created for the substances or energy obtained. Until these criteria are satisfied, the wastes cannot be properly disposed of.
Published German patent application No. DE 3,725,528 discloses an apparatus for pressing or dewatering suspensions, sludges or the like. It has been found, however, that even under high pressures it is not possible to remove the oil adhering to the wastes.
Despite the foregoing state of the art, there remained a need for methods and apparatus for disposing of residues from machining of metals.